The present invention relates to a new and improved apparatus for actuating the hoistway or shaft doors of an elevator or the like, which is of the type comprising a fixed coupling element arranged at the hoistway or elevator shaft door and a movable, electromagnetically actuatable coupling element arranged at the elevator door, this movable coupling element, at the region of an elevator landing, can be brought into engagement with the fixed coupling element of the hoistway door.
Such type apparatuses have the purpose of continuously and synchronously opening and closing, respectively, horizontally displaceable elevator cabin and hoistway doors by means of a door drive mounted at the elevator cabin when the latter reaches a landing or storey.
Now in British Pat. No. 587,984 there is disclosed apparatus for simultaneously actuating the elevator cabin and hoistway doors of an elevator system, wherein an electromagnet arranged at the elevator cabin is actuated by a coupling element movably mounted at the elevator cabin door through the agency of a lever rod. The coupling element possesses a substantially wedge-shaped cross-sectional configuration and, when the electromagnet is energized, is retained in its uncoupled position. The fixed coupling element mounted at the hoistway door has a substantially V-shaped groove which is essentially complementary in shape to the wedge-shaped cross-section of the movable coupling element. When the elevator stops at a landing the electromagnet is deenergized and both of the coupling elements can come into engagement under the action of spring force.
Another prior art apparatus as taught in U.S. Pat. No. 1,876,438 has the electromagnet mounted directly over the movable coupling element in the cabin door and connected therewith by a hinge or pivot arrangement. The movable coupling element is retained in its uncoupled position under the force of gravity, whereas when the electromagnet is energized it comes into engagement with the fixed coupling element mounted at the hoistway door.
The previously described door actuation devices are especially associated with the drawback that both of the coupling elements must be situated exactly opposite one another during the coupling operation. In other words: no deviations can be present in the direction of the door movement between the coupling elements.
This drawback is avoided to a certain extent with the further state-of-the-art door drive apparatus disclosed in Swiss Pat. No. 523,199. With this apparatus the movable coupling element comprises an entrainment parallelogram arranged at the elevator cabin door and collapsed or pushed together in the uncoupled state thereof. This entrainment parallelogram is connected with a door drive arranged at the cabin by means of a sliding crank drive. The door drive is constructed as a thrust crank drive. Two rolls rotatably mounted upon pins or journals constitute the fixed coupling element and are provided at the elevator shaft or hoistway door. When the elevator cabin approaches a target landing, then the entrainment parallelogram is driven by the door drive which has started-up in the meantime so that upon introduction between both of the rolls the entrainment parallelogram is shifted from its collapsed into its spread position and bears at the rolls for the purpose of entraining the hoistway door free of play.
A disadvantage of this apparatus resides in that it is of relatively complicated construction. A further drawback is present by virtue of the fact that the door drive starts to run and the entrainment parallelogram spreads before the elevator cabin has reached the target landing or storey, so that part of the play is lost. Hence, only extremely small deviations are possible between the coupling elements. However, such apparatus is not suitable for use where there are present larger lateral deviations, such as for instance can occur with inclined elevators. Additionally, in this field of application the entrainment parallelogram in its uncoupled state, must be drawn considerably upwardly, in order to be able to move past both of the rolls when travelling past a stop location. This requires, on the one hand, a considerable amount of space and, on the other hand, leads to different lengths of coupling paths, depending upon the momentary inclination angle of the path of travel, so that the time for opening the door becomes relatively large.